1. Field of the Invention
The present invention relates to a liquid-crystalline polyester and a solution composition containing the liquid-crystalline polyester. The present invention also relates to a film of the liquid-crystalline polyester and the like.
2. Description of the Related Art
Recently, with increasing requirements for light-weight, high-density and small-size electric and electronic parts in the market, the application of flexible printed wiring boards and the like are being enlarged (as, for example, in complex parts having wiring, cable, connecter or the like) because of its flexibility, large space freedom and availability in practical installment with sterically high density.
The flexible printed wiring board can be produced by laminating a metal foil onto an electrical-insulation base film and preparing a circuit. The base film having a high flexibility has been eagerly anticipated.
One of known base films is obtained, for example, by a method of applying a solution composition comprising an aprotic solvent and a liquid-crystalline polyester having a structural unit derived from aromatic amine onto a support and removing the solvent (see, JP-A-2004-315678, corresponding to U.S. Pat. No. 7,022,807). While the base film obtained by such a method has a high flexibility, it is demanded to provide a base film having not only high flexibility but also good dimensional stability.
In order to prepare a base film having a high dimensional stability, a method of adding fillers is also known. However, the base film containing fillers tends to have a lowered flexibility. In addition to the dimensional stability, it still has been desired to develop a film which is difficult to curl up (or having a small curling property) in a laminate with a conductive layer or in a flexible printed wiring board.